Shown below is a triangular prism of height 10 cm. Calculate its volume.

(Note: Volume = Area of cross section × height.)

The volume of the prism is cubic cm.

Find the area of triangle $\mathrm{PQR}$ formed by the points $\mathrm{P}\left(-5,7\right),\mathrm{Q}\left(-4,-5\right)$ and $\mathrm{R}\left(4,5\right)$.

Find the area of the triangle formed by joining the middle points of the sides of the triangle whose vertices are $\left(0,-1\right),\left(2,1\right)$ and $\left(0,3\right)$.

Find the area of the quadrilateral whose vertices are $\left(-3,4\right),\left(-5,-6\right),\left(4,-1\right)$ and $\left(1,2\right)$.

Find the area of the triangle formed with the three straight lines represented by:

$$\begin{gathered} \left(i\right) x+y=0 \\ \left(ii\right) 3x = 5y; and \\ \left(iii\right) y=3x-12 \end{gathered}$$